Work steering and feeding mechanism



1962 H. F. SCHAEFER, JR 3,051,476

WORK STEERING AND FEEDING MECHANISM Filed Oct. 10, 1960 9 Sheets-Sheet 1 Invert far" I Hans F Sc/mefer; Jr By his Attorney ail/WW.

1962 v H. F. SCHAEFER, JR 3,051,476

WORK STEERING AND FEEDING MECHANISM Filed 001;. 10, 1960 9 Sheets-Sheet 2 0 36 o 32 I 0 /2 00 a4 748 (6 140 1 10/ 70 144 I 20 a2 l I #2 7/6 x I /42 m g 76 706 J Aug. 28, 1962 H. F. SCHAEFER, JR 3,

WORK STEERING AND FEEDING MECHANISM 9 Sheets-Sheet 3 Filed Oct. 10, 1960 Aug. 28, 1962 H. F. SCHAEFER, JR 3,051,476

WORK STEERING AND FEEDING MECHANISM Filed Oct. 10, 1960 9 Sheets-Sheet 4 1952 H. F. SCHAEFER, JR 3,051,476

'WORK STEERING AND FEEDING MECHANISM 9 Sheets-Sheet 5 Filed Oct. 10, 1960 1962 H. F. SCHAEFER, JR 3,051,476

WQRK STEERING AND FEEDING MECHANISM Filed Oct. 10, 1960 9 Sheets-Sheet 6 Aug; 28, 1.962 H. F. SCHAEFER, JR 3,051,476

WORK STEERING AND FEEDING MECHANISM 9 Sheets-Sheet 7 Filed Oct. 10, 1960 Aug. 28, 1962 H. F. SCHAEFER, JR 3,0

WORK STEERING AND FEEDING MECHANISM Filed Oct. 10, 1960 9 Sheets-Sheet 8 1962 H. F. SCHAEFER, JR 3,051,476

WORK STEERING AND FEEDING MECHANISM Filed Oct. 10, 1960 9 Sheets-Sheet 9 Pl/om CELL POTENTIOMETER SERVO SERVO MOTOR AMPLIF/[R United States Patent Ofifice 3,951,476 Patented Aug. 28, 1962 3,051,476 WORK STEERING AND FEEDING MECHANISM Hans F. Schaefer, Jra, Rockport, Mass, assignor to United Shoe Machinery Corporation, Fiemington, N.J., a corporation of New Jersey Filed Oct. 10, 1960, Ser. No. 61,436 12 Claims. (Cl. 2711) This invention relates to the provision of controlled, variable directional feed mechanism for guiding generally fiat work pieces. More particularly this invention is concerned with providing improved means for advancing and guiding flexible sheet-like material such as leather, paper, and plastics, for instance, with respect to a tool arranged to operate in a curvilinear path thereon. Although herein illustrated as embodied in a machine for progressively folding the edges of irregularly shaped pieces of leather, the invention is not thus limited but is considered especially advantageous for use in a wide variety of machines the tools of which are adapted to operate on the work in curvilinear as well as straight and/or angular paths.

Work feeding mechanisms of the so-called four-motion type have commonly been employed in stitching, perforating, eyeletting, and many additional machine types used in shoe manufacture and otherwise in industry. In these mechanisms the work is engaged by a feed element that is moved in translation to advance the work rectilinearly, whereupon the element is disengaged and returned in a closed path to reengage the work and repeat its work advancing step. The work is thus, in successive increments, controlled for movement in a machine in one invariable direction, and customarily a needle, punch, setting or other tool of the machine may be caused to operate upon the work to provide, for instance, a straight line seam, series of imprints or perforations, or row of fasteners, etc. It will be apparent, however, that an operating tool frequently must also function along paths which are not straight, and it then usually becomes a tedious, fatiguing and difficult task manually to guide the work pieces in the required manner relatively to the tool.

In view of the foregoing, it is a primary object of this invention to provide an improved feed mechanism by means of which variable directional movement of a work piece may be automatically controlled to steer it with respect to an operating tool in straight and/or curvilinear paths as determined by a pattern. A further and more specific object of the invention is to provide, in combination with a machine having means for operating on or near the edge of a work piece of irregular contour, a simplified step-by-step feed mechanism electrically responsive to the curvature of successive edge portions of the work approaching the operating means for appropriately modifying the direction in which the work piece is fed past said means. Yet another object of this invention is to provide a versatile, economical edge shaping machine which is easy to operate by an unskilled attendant.

In accordance with these objects, a feature of the invention resides in the provision, in a machine for operating on sheet material, of a feeding element, mechanism for imparting to the element movements for advancing the material in steps of translation, and work guidance means responsive to a pattern (for instance the contour of the material itself) for variably shifting said feeding element transversely of a rectilinear path in the course of its translatory feeding steps to steer the material in the machine. As will be appreciated by those experienced in the art, machines for edge folding and other apparatus adapted to operate on flexible, irregularly shaped work piece margins have hitherto required that a high degree of operator skill and close attention be practiced in properly guiding each piece of material to be shaped or treated.

As herein shown the feeding element illustrating feed movements for directionally guiding a work piece is in the form of a mechanically actuated clamp or hammer which, in this instance, is also advantageously employed to pound the progressively folded margin of a leather vamp or the like as it is fed. In the illustrative machine, and in accordance with a further feature of the invention, automatic work guidance mechanism controlling the hammer in its directional feeding is disclosed, and as shown herein this guidance mechanism comprises a photoelectrically controlled circuit together with suitable amplifier means responsive to the curvature of the pattern provided by the margin to be cemented and edge folded. Accordingly, in the illustrative arrangement, in addition to a fixed turning post or plow for progressively turning up the edge of the work as it is fed to be pounded back upon itself by the hammer in the course of feeding, there is provided a nozzle for delivering adhesive to the Work piece margin just ahead of the work-engaging locality of the turning post. While the nozzle may be considered as simply a stationary tool, it will be apparent that any operating tool, stationary or movable relatively to the work (such as a reciprocable cutter or needle), may be employed in combination with the novel work feeding and guiding means with which this invention is especially concerned.

In the machine as herein shown, an anvil advantageously cooperates with the hammer in pressing successive increments of the folded margin during their step-by-step feeding past the turning post. Hence, in this exemplary arrangement the anvil is required to participate equally and simultaneously with the hammer in any directional deviations from straight line feeding dictated by the guiding or curvature sensing mechanism. Thus, a carrier for the hammer and anvil, in addition to being mounted for swinging movement in a single plane of feed, is pivoted to swing about a vertical steering axis at right angles to the plane of normal swinging movement. Deviation from straight line feed results from turning the carrier about said steering axis and is controlled by a servo motor responsive to the above-mentioned circuit, the steering axis preferably always intersecting the work-engaging surface of the turning post.

The above and other features of the invention, together with various novel details of construction and combinations of parts, will now be more particularly described in connection with an illustrative machine in which the invention is embodied and with reference to the accompanying drawings thereof, in which:

FIG. 1 is an angular view in elevation of a front portion of an edge folding machine incorporating the novel work guiding mechanism;

FIG. 2 is a view similar to FIG. 1 but with a work supporting table omitted and taken from a different angle again showing a portion of the guiding means;

FIG. 3 is a view in front elevation, with parts broken away, and on a larger scale to show mechanism for operating the work guidance means;

FIG. 4 is a plan view of feed control mechanism shown in FIG. 3;

FIG. 5 is a view in side elevation of the mounting of curvature sensing means shown in FIGS. 3 and 4;

FIG. 6 is a view in side elevation and partly in section of a hammer and anvil and driving mechanism associated therewith;

FIG. 7 is a section taken on the line VII-VII of FIG. 6;

FIG. 8 is an exploded perspective view of resolver mechanism partly shown in FIG. 6, the parts being in neutral or straight-feeding position;

FIG. 9 is a detail view in transverse section taken on the line IX-IX of FIG. 8;

FIG. 10 isan exploded perspective view of hammer operating means shown in FIG. 6;

FIG. 11 illustrates a vamp one edge of which has been directed and folded by the machine of this invention;

FIG. 13 is a plan view of a work piece in the machine, companion FIGS. 12 and 14 illustrating corresponding positions of parts operating at this stage to steer the work to one side of straight-line feed;

FIG. 16 is a plan view corresponding to FIG. 13 and having companion FIGS. 15 and 17 similar to companion FIGS. 12 and 14, respectively, but now illustrating their relative positions to steer the work to the other side of straight-line feed;

FIG. 18 is a schematic diagram of hammer and anvil operating paths and corresponding positions of a resolver shown in FIGS. 12 and 15; and

FIG. 19 is a block diagram of the mechano-electrical control system of the machine.

In some respects the illustrative machine resembles an edge folding machine disclosed in United States Letters Patent 2,720,667, issued October 18, 1955 upon an application filed in the name of W. E. Naugler. In that patent, as well as in a somewhat structurally similar earlier arrangement disclosed in United States Letters Patent No. 2,270,891, issued January 27, 1942 in the name of C. A. Newhall, a hollow machine frame 10 (FIGS. 1 and 2) and its forwardly extending arm 12 respectively afford bearings for a main shaft (not shown but corresponding to the shaft designated 42 in the above cited patents) and a parallel rock shaft 14 (FIG. 3). The arm 12 includes a removable end portion 16 secured thereto by a socket screw 15 (FIGS. 1 to 3 inclusive). Secured to the frame 16 on a level with the upper surface of the arm and its portion 16 is a table 17 (FIGS. 1 and 3) over which the work to be operated upon will be fed intermittently as will be explained. Resembling the mentioned prior construction, in order to hold the work against movement in intervals when reciprocable work feeding and guiding. means, comprising work engaging jaws in the form of a hammer 18 and an anvil 20 (FIGS 1, 3 and 8), is returning to its initial position, an elongated gripper or lower clamping member 22 (FIGS. 1, 3, 4 and secured to the front end of the rock shaft 14 is raised in a slot of the table 17 to grip the work against the under surface of a yieldable clamp lever 24. The latter, as indicated in FIG. 3, is pivoted on a screw 26 in an overhanging neck of the frame For yieldably determining the normal position of the lever 24, its extension arm 28 is connected by a tension spring 30 (FIGS. 2 and 3) to a setscrew 32 adjustably threaded into. a bracket 34 secured to the overhanging neck. The spring 34) thus urges the lower end of the clamp lever downwardly into work-engaging position to the extent adjustably permitted by a screw 36 threaded through the bracket 34 for endwise engagement with the upper end of the lever 24.

Disposedsubstantially in a line with the work clamping zone of the members 22, 24 is a fixed turning post 38 (FIGS. 3, 4, 8 and 13) havinga'finger 40 projecting upwardly from the arm 12 and against which the margin of each work piece is urged to be folded as it is fed. A cementing nozzle '42 (FIGS. 1, 2 and 13) is arranged to deliver adhesive to the margin of the work just ahead of the turning post, and just beyond the turning post in the direction of feeding the hammer 18 cooperates with the anvil 20 intermittently to pound, seize, and advance successive marginal increments in translation and in an angularly variable feeding direction determined by steering means hereinafter to be explained.

Referring to FIGS. 6 and 8, a hollow rock shaft 44 is journaled in the frame 10 and is oscillated about a horizontal axis to impart feeding movements to the hammer 18 and anvil 20', the shaft being operatively connected to the above-mentioned. main shaft by mechanism fully described and illustrated in the cited Naugler patent and not herein disclosed. In order to operate the hammer heightwise and in proper timed relation relatively to the anvil, a shaft 46 (FIGS. 6 and 10) is axially reciprocable in the shaft 44 and also is operatively connected to the main shaft as described and illustrated in the patent to Naugler. For convenience in explaining the work guidance to be imposed during step-by-step feeding by the hammer and anvil, a fixed and nearly vertical axis is designated A, (FIGS. 8 and 18) and extends substantially through a work-engaging point P (FIGS. 4 and 8) on the turning post finger 40 from which each feeding stroke may be considered to commence. Each time the hammer and anvil advance from the point P they either feed the work along a straight line such as will advance the edge to the point S in FIG. 18, or they are caused, by automatic steering means hereinafter to be explained, jointly to deviate from the straight path to the right or the left a variable amount determined by the steering means, for instance to such points as are designated R or L, respectively, in FIG. '18. The axis about which the rock shaft 44 oscillates coincides (but only during straight ahead feeding) with an axis designated B in FIGS. 8 and 18 and it intersects the axis A at a fixed point of intersection x which also lies on a later-mentioned axis C (FIGS. 8 and 18.) of the steering means. The latter, as later explained, causes deviation from straight ahead feeding whereby the axis B is appropriately swung about the point x.

The mounting of the hammer and anvil and their straight ahead feed actuating mechanism will now be further described. Referring to FIGS. 1 and 2, an angular bracket 58 is secured to the portion 16 by the screw 15 and adjacent dowel pins. Secured to this bracket for turning about the axis A, as limited by the steering means, is a support 54 (FIGS. 6 and 8) provided with a sleeve bearing for receiving a stem 56 (FIG. 6) of a hammer and anvil carrier 53 (FIGS. 6 and 8) formed, for a reason later mentioned, with a semicircular channel 68. The axis of the stem 56 and its supporting sleeve constitutes the axis B which is thus pivotal about the axis A in a plane at right angles to the plane of straight feed oscillation of the hammer and anvil. A nut 62 is threaded onto the stem 56 for holding the carrier in pivotally assembled relation to the support 54. A hardened insert 64- (FIG. 6) of the anvil 2A is mounted in a dovetail formed in a split clamp portion of the carrier 58 and secured by a clamping screw 66. A rearwardly extending upper portion of the carrier is journaled to receive a horizontal pin 68 for pivotally mounting in its forked portion a lever 78 the upper end of which constitutes the hammer 18. The lower end of the lever in is operatively connected to the shaft as as will next be explained.

Referring mainly to FIGS. 8, 9 and 10, the forward end portion of the oscillatory feed shaft 44 has a tubular enlargement axially slotted slidably to receive a key 74- integral with a hollow end portion 76 of the reciprocable shaft 46. For urging the hammer 18 normally to assume a closed or gripping position relatively to the anvil 20, an annular plug 78 is adjustably threaded into the portion 76 and abuts one end of a compression spring 86 (FIGS. 6 and 8) the other end of which engages rounded head of a plunger 82 to hold it in abutting relation to the shaft 46. This plunger extends through the plug and is threadedly received by and clamped to a bearing block 84 rotatably supporting a pin 86. Extending through the latter is a vertical swivel pin 88 anchored in the lower end of the lever 78. Swinging movement of the hammer and anvil carrier 58- about the angularly shiftable horizontal axis B to feed the work is effected through mechanism constituting a universal joint later to be described and a swivel joint next to be explained coupled to the shaft 44. Upper and lower bearing blocks 90, 90 (FIGS. 6, 9 and 10) integral with the feed shaft 44 are respectively bored to receive alined trunnion pins 92, 92 which project respectively through upper and lower flanges of a carrier tilting lever 94 (FIGS. 6, 8 and 9) functioning as hereinafter mentioned. The trunnion pins 92 are secured by setscrews 96, 96 respectively threaded into the blocks 98 and through rotation-limiting blocks 98, 98 respectively. When the work has been advanced a step by oscillatory movement of the shaft 44, the lever 94, and corresponding movement of the carrier 58, axial movement of the shaft 46 to the right as viewed in FIGS. 6 and 10 is effective similarly to move the spring 80 and the rod 82 together thus to lift the hammer 18 and permits its return movement together with the anvil 20 while the clamps 22, 24 hold the work against any possible retrogressive influence. The shaft 46 is retracted to the left to close the hammer 18 upon the work. The arrangement is such that although the shaft retraction is to a fixed point, the spring 80 is compressed only if the hammer engages a work piece, this compression enabling various thicknesses of stock to be accommodated.

In order to steer curved peripheral portions of the work about the turning post so that cement from the fixed nozzle 42 may be appropriately located on the next marginal increment and the latter folded along the correct line, and so that an adjacent marginal increment which has just been cemented may now be correctly and uniformly folded, the hammer and anvil must either be shifted during feeding strokes to the left of neutral as indicated in FIG. 13, or to the right of neutral as indicated in FIG. 16 depending on work piece configuration. Accordingly, in addition to neutral swinging movement in a single vertical plane as effected by mechanism thus far described, the hammer and anvil carrier 58 is caused to swing about the vertical .axis A in an are appropriate to perimeter curvature in the zone of operation by servo controlled steering means generally designated 100 (FIGS. 1 and 8) about to be explained, the work thus always being turned about the turning post, but without the use of any differential feed wheel system. The means 100 includes a balancing potentiometer 101 (FIGS. 1 .and 19) of conventional type, and a servo motor 102 (FIGS. 1 and 4) having an output gear 104 arranged to mesh with a bevel gear 106 (FIGS. 2, 3, 4 and 8). This gear is secured to a shaft 108 the outer end of which mounts the potentiometer. The shaft is rotatably supported in a bore formed in an L-shaped block 110 (FIGS. 3 and 8) which is .afiixed to the bracket 50. The other end of the shaft 108, the axis of which has been designated C in FIG. 8, carries a resolver 112 (FIGS. 2, 8, 1 2, 15 and 19) formed with an arcuate guideway 114 for slidably receiving a segment 116. The guideway and the periphery of the segment are concentric about the point x. As indicated in FIG. 18, when the resolver guideway 114 is disposed vertically, the hammer and anvil feed the work straight ahead, i.e. there is no directional deviation from neutral. When the guideway 114, by reason of positional control exerted by the servo motor 102, is turned from its vertical position and about the axis C as indicated in FIG. 18, or correspondingly in FIGS. 12 and 13, the segment 116 is constrained angularly, upon being swung downwardly relatively to the resolver by operation of the lever 94, to shift the axis B horizontally about the point x of the hammer and anvil carrier 58 as will next be explained.

The segment 116 has a bore 118 alined with a bore 119 (FIG. 8) formed in a retaining plate 120 (FIGS. 3 and 8) secured to, and constituting one side of, the carrier 58. The opposite side of the carrier is bored rotatably to receive one end of a short shaft 121 secured in the bore 118 and extending through the bore 119. The shaft 121 is formed with a segmental gear 122 for meshing with internal teeth 124 formed on a portion of a somewhat ringshaped yoke or tiltable driving key 126 (FIGS. 3, 6-8). The teeth 124 are disposed in the channel 60. The yoke is formed with opposite, enlarged bearing localities 128,

128 and a spaced, parallel bearing enlargement 130 (FIGS. 7 and 8) thus determining what is in effect a pair of parallel, tiltable axes Y, Z (FIGS. 14 and 17) arranged on opposite sides of the axis A and constituting the aforementioned universal joint connecting the carrier 58 and its actuating lever 94. For rocking the yoke 126 while permitting its hinge axes Y and Z to be tilted as determined by the aforementioned rotation of the resolver 112, the carrier tiling lever 94 is formed at its forward end with a crescent-shaped plate 132 (FIG. 8) to which a bearing plate 134 is keyed and secured by a bolt 136, the localities 128, 130 being frictionally engageable with these plates, and the enlargement 130 having line contacts with the opposite walls of the channel 60.

Work steering, i.e., angular positioning of the resolver 112 by the servo control means 100 is continuously determined by a curvature sensor, in this case a photoelectric cell (FIGS. 2, 3, 5, 8, 13 and 16) adjustably mounted at one side of a work piece to receive light transversely passing its unfolded edge from a source such as a bulb 142 and traveling through a bent Lucite rod 144 disposed on the opposite side of the work. It will be understood that the table 17 is suitably formed not to interfere with the beamed light, rays of which are intercepted by the work edge in the manner of a shutter, if at all, in a locality just ahead of the cement nozzle 42. The arrangement is such that a standard reference level of light is received by the cell for zero error or straight line feeding, and the greater the departure from this level, the stronger the cell signal for correction by the servo motor and the greater corresponding tilt from vertical imparted to the segment116 and consequently to the shift of axis B. It will be understood that the motor 102 is then also acting appropriately to shift the movable con-tact of a resistance element (not shown) of the potentiometer 101 thus to match the balancing signal from the potentiometer 101 to the signal from the photocell 140. Comparing FIGS. 13 and 16, it will be apparent that in FIG. 13 the work curvature is tending to uncover the cell 140 thus allowing more than a predetermined neutral or zero level to pass and permitting it to signal the servo motor 102 via suitable circuitry including amplifier means (FIG. 19) for angular shifting of the resolver 112 about the axis of the shaft 108 as shown by broken lines in FIG. 12 and consequent tilting of the axis Z in one direction. Resultant turning of the carrier 58 about the axis B during the feed stroke is indicated in FIG. 14. FIG. 16, on the other hand, illustrates work contour tending to reduce the incidence of controlling light upon the cell beneath the zero level; consequently the signal to the motor 102 now acts reversely to shift the resolver 112 as noted in FIG. 15 with consequent opposite tilting of the axis Z and appropriate shifting of the carrier 58 as shown in FIG. 17. Upon return to a straight line path of operation it will be understood that the potentiometer 101 serves to return steering control to neutral.

In order to take up backlash, if any, between the actuating parts, a compression spring 146 (FIGS. 3 and 8) is half nested in the resolver 112 and in the segment 116. An abutment 148 (FIGS. 2, 4, and 8) on the gear 106 is arranged to engage stop screws 150, 150 adjustably threaded into the block 110 thus to limit resolver rotation within an arc wherein jamming of parts is avoided.

From the foregoing it will be clear that by use of this invention numerous operations may be performed along the margins of irregularly shaped work pieces without the need of continuous operator attendance, it sufficing merely to present each piece initially to the feeding instrumentalities in order that they may thereafter guide the work automatically with respect to the operating tool. The shoe vamp shown in FIG. 11 which has had its upper edge folded in the machine is thus but one illustration of marginal processing conveniently accomplished with the aid of the automatic work steering means herein disclosed. Too, it will be appreciated that, while these means are i1- lustrated as being under the control of curvature sensing means adapted to cooperate with the work edge in the fashion of a shutter, the sensing means may in other suitable casesbe arranged, if desired, to cooperate in similar manner with selected curvatures other than at the perimeter of the work.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A machine for progressively operating on a work piece the margin of which is curved comprising an edge gage, a work support on which a work piece is to be automatically guided for movement relatively to the gage, feeding means arranged intermittently to engage, advance, and release the work to effect step by step translation thereof relatively to the gage, and curvature sensing means for causing said feeding means directionally to deviate during its advance to steer the work in accordance with the curvature, being sensed.

2. A machine for progressively operating on a work piece the margin of which is curved comprising an edge gage, a support on which the work piece is to be automatically guided relatively to the gage, cyclically operative feeding means including a member movable into and out of engagement with the work piece at one side of the gage to advance and release the work piece in successive increments as the work piece is thus moved past the gage, and curvature sensing means acting on successive incremental portions of the work piece on the other side of the gage to control steering deviation relatively to the gage of said member while it engages the work.

3. A machine for progressively operating on curved portions of sheet-like work pieces comprising an operating tool, a work support adjacent thereto on which a work piece is to be automatically guided for movement with respect to the tool, a pair of cooperative feeding members arranged intermittently to engage, advance, and release the work to elfect its step by step translation relatively to the operating zone of the tool, and curvature sensing means for causing said feeding members to deviate directionally during their advances to steer the work in accordance with the curvature being sensed.

4. A machine as set forth in claim 3 wherein at least one of said members is driven in a closed orbital path, work clamping means is operable to engage the work adjacent to the engagements of said one member therewith, and power means is provided for alternating the work engagements of the clamping means with those of the work advancing movements of said member to hold successive portions of the work against retrogressive movement.

5'. A machine as set forth in claim 3 wherein the cooperative members are cyclically closable jaws, carrier means mounting said jaws for oscillatory movement in unison, and said sensing means is effective to cause swinging of the carrier means during closure of the jaws upon the work to steer it in the course of their advances.

6. Work feeding mechanism for guiding a work piece on a table with respect to an operating tool comprising a pair of Work gripping jaws, a carrier mounting said jaws for oscillatory movement in unison and about an angularly shiftable axis, mechanism for oscillating the carrier about said axis to impart straight-line feeding to its jaws, means for relatively closing said jaws during their advance and opening them during their return movement,

and curvature sensing means cooperative with said mechanism for causing said axis to be shifted about a point during the advance of said jaws whereby they are caused to deviate from straight-line feeding according to the degree of curvature being sensed.

7. A machine as set forth in claim 6 and further characterized in that said sensing means comprises a source of light positioned at one side of a Work piece on said table, a light responsive cell arranged to receive light directed transversely of the work edge from said source, a servo motor, and circuitry interconnecting the cell and the motor continuously to position angularly the axis about which said jaws oscillate in accordance with the intensity of the light incident upon said cell.

8. A work feeding mechanism for steering a work piece on a table with respect to an operating tool comprising a pair of jaws oscillata-ble in unison about an axis angularly shiftable about a point, means for thus oscillating the jaws, means for urging the jaws into cooperative work engaging position as they move in a direction to feed the work relative to the tool, and work steering means for angularly shifting said axis about said point according to the curvature of successive increments in the margin of the work piece in the locality approaching said tool.

9. In a machine having a tool for operating on a work piece on a table, means engageable with the Work in the vicinity of the tool for automatically feeding and steering the margin of the work with respect thereto, said means comprising an edge gage, an oscillatory work-engaging element for advancing successive portions of the margin past said gage, and sensing means responsive to the curvature of the margin in the locality approaching the gage, said sensing means having operative connection to said element angularly to shift the axis about which it oscillates in accordance with the curvature sensed.

10. Work guidance mechanism for a machine of the type having cooperative jaws arranged to seize and advance successive portions of the work, said mechanism comprising a carrier for said jaws, means mounting the. carrier for oscillation about an axis angularly shiftable about a point in a horizontal plane, means for closing said jaws on the work at the start of each oscillation and for opening them as it terminates, and steering means responsive to work curvature for controlling the angular shifting of said axis, the last-mentioned means including a photoelectrically controlled servo motor having operative connection with said carrier.

11. Mechanism as set forth in claim 10 wherein the operative connections of said servo motor comprise a resolver, a carrier drive key controlled thereby, means for oscillating the carrier, and universal joint means inter. connecting the carrier to the means for oscillating the latter.

l2. Mechanism as set forth in claim 11 and further characterized in that a shaft mounting said resolver for rotation about an axis is provided, and a balancing potentiometer is operatively connected to said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 2,259,502 Topham et al. Oct. 21, 1941 2,720,667 Naugler Oct. 18, 1955 2,900,934 Judelson Aug. 25,, 1959 

